Author(s)

A.S.H. Prevot, J. Dommen and M. Baumle

Abstract

Morning VOC Concentration Minima in the Mesolcina Valley During the VOX ALP Experiment A contribution to subproject LOOP ASH Prevot\ J Dommen* and M. Baumle^ * Air Pollution Division, Paul Scherrer Institute CH-5232 Villigen-PSI, Switzerland ^MetAirAG, CH-8308 Illnau, Switzerland During the EU VOTALP (Vertical Ozone Transport in the ALPs) project we performed an intensive field campaign in the Mesolcina Valley to study vertical exchange mechanisms of atmospheric constituents between the boundary layer and the free troposphere. Low VOC (Volatile Organic Compound) concentrations in the morning were found by aircraft and ground based measurements on days when northerly winds prevailed in the upper part of the valley during the night, yielding transport of cleaner air from high altitude into the valley core. On nights with winds from the south, the pollutant levels including ozone rema

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